Why we are unlikely to ever leave the solar system. • Hacker News Board

Re: Why we are unlikely to ever leave the solar system.

#161

Post by Dn_Ab » Fri, Jun 10, 2011, 10:45 PM UTC

scott_s wrote: post #151

forgottenpaswrd wrote: post #108

Oh, the ego, what a marvelous thing! Believing that what we currently know is applicable to humans in the future, that our current limits are immutable. We know all the laws of physics, right? We know if the universe is finite or infinite(because we had traveled there and seen the limits), we know what creates gravity and exactly how electromagnetic attraction really works... the same way the people Socrates asked 25…

We actually know what gravity really is (basically, curving of space due to mass), and we know why the speed of light is the speed limit of the universe (it's necessarily true because space is continuous and you can't teleport). These come from general relativity, which is an extremely well test theory. Whatever we find out about gravity and light in the future must at least reduce to general relativity. What I find…

I don't disagree with your sentiment - any future theory must hold to current theories at its limit. But I disagree that we know what anything really. To know what gravity is really we must answer. What is mass, space, time, spacetime, inertia? Is the graviton real? Is space continuous or discrete? Also note curving of space is due to more than mass lest how would light beams be gravitationally responsive? Curvature is described by the stress energy tensor.

What we do have are human graspable descriptions of plausible moves based on our observations of chess pieces. We have no coherent theory on the game or why it is played. But that does not matter. A more important issue intertwined with this bias is: are notions of information and entropy more fundamental to how we formulate laws than anything intrinsic to energy and space?

Re: Why we are unlikely to ever leave the solar system.

#162

Post by juretriglav » Fri, Jun 10, 2011, 10:59 PM UTC

Detrus wrote: post #15

cletus wrote: post #6

That's a good, grounded assessment of the scale of the problem. I too believe that the human colonization of space, even near-space (ie within the orbit of the Moon) is a long way off. The energy costs are simply too high and resources too cheap on the Earth to make it viable (in spite of typical SF fodder of asteroid mining). This is a problem because with 6.5 billion people we're using up resources. Fast. Anyway, I…

Black holes spaceships are the ticket with our current understanding of physics. They can carry a large and heavy cargo in ship form or can push small planets slowly in a desired direction. The travel times for black hole ships are reasonable too, about six years to Proxima Centauri. It beats the other sci-fi concepts like fusion, Orion, anti matter and solar sails. Funny how solar sails seem like the easier option t…

For those of you who, like me, thought a black hole spaceship is a spaceship travelling through black holes, I made an awesome diagram of how it's supposed to work.

http://www.juretriglav.si/images/blackholespaceship.png

Re: Why we are unlikely to ever leave the solar system.

#163

Post by VladRussian » Fri, Jun 10, 2011, 11:02 PM UTC

cpeterso wrote: post #146

Detrus wrote: post #15

Earlier quoted context omitted.

Black holes spaceships are the ticket with our current understanding of physics. They can carry a large and heavy cargo in ship form or can push small planets slowly in a desired direction. The travel times for black hole ships are reasonable too, about six years to Proxima Centauri. It beats the other sci-fi concepts like fusion, Orion, anti matter and solar sails. Funny how solar sails seem like the easier option t…

If we can't travel faster than the speed of light (a reasonably safe assumption), maybe we can take intergalactic shortcuts like black holes. So it seems to me that Battlestar Galactica-style "jump" drives (or Borg transwarp conduits) are more likely than Star Trek-style warp drives.

>If we can't travel faster than the speed of light

using existing understanding of Nature - we can. At least the Universe provides the example of galaxies traveling with faster than the speed of light relative to each other. The same machinery is suggested in the

http://en.wikipedia.org/wiki/Alcubierre_drive

The opponents state that the energy requirement of the drive is higher than the whole Universe's energy. Obviously it is wrong statement as we already have whole galaxies mentioned above and whose faster than light speed obviously takes less than the whole Universe's energy.

Re: Why we are unlikely to ever leave the solar system.

#164

Post by inklesspen » Sat, Jun 11, 2011, 12:25 AM UTC

VladRussian wrote: post #163

cpeterso wrote: post #146

Earlier quoted context omitted.

If we can't travel faster than the speed of light (a reasonably safe assumption), maybe we can take intergalactic shortcuts like black holes. So it seems to me that Battlestar Galactica-style "jump" drives (or Borg transwarp conduits) are more likely than Star Trek-style warp drives.

>If we can't travel faster than the speed of light using existing understanding of Nature - we can. At least the Universe provides the example of galaxies traveling with faster than the speed of light relative to each other. The same machinery is suggested in the http://en.wikipedia.org/wiki/Alcubierre_drive The opponents state that the energy requirement of the drive is higher than the whole Universe's energy. Obvio…

Galaxies are not actually moving faster than light. The distance between them is growing at a rate that would suggest FTL speeds because the universe is expanding.

Re: Why we are unlikely to ever leave the solar system.

#165

Post by cheez » Sat, Jun 11, 2011, 12:26 AM UTC

juretriglav wrote: post #162

Detrus wrote: post #15

Earlier quoted context omitted.

Black holes spaceships are the ticket with our current understanding of physics. They can carry a large and heavy cargo in ship form or can push small planets slowly in a desired direction. The travel times for black hole ships are reasonable too, about six years to Proxima Centauri. It beats the other sci-fi concepts like fusion, Orion, anti matter and solar sails. Funny how solar sails seem like the easier option t…

For those of you who, like me, thought a black hole spaceship is a spaceship travelling through black holes, I made an awesome diagram of how it's supposed to work. http://www.juretriglav.si/images/blackholespaceship.png

How the heck do you hold the black hole in place?

Re: Why we are unlikely to ever leave the solar system.

#166

Post by jberryman » Sat, Jun 11, 2011, 1:43 AM UTC

drcube wrote: post #155

troutwine wrote: post #154

Earlier quoted context omitted.

Climate shift implies a necessary change to infrastructure: cities that once did not have to deal with flash floods will, for example. Municipal trees will die. Areas that grow colder will have non-insulated water pipes burst. There is no need to form greater bureaucratic nightmares to adapt for such problems, only a general willingness to remake our urban environments before it becomes dreadfully expensive. Note the…

But how much will forcing those infrastructure and cultural and societal changes cost NOW, versus letting them happen naturally and gradually the same way we switched from wood to coal to petroleum and from muscle to steam to electricity? Extremely simple illustration: Do you think people in Florida will be living 10 feet under water in 100 years? No, they will move before then. But they don't have to move now, so wh…

...to coal to petroleum

The fact that you think humans have by any means made the technological "leap" from coal to petroleum (or anywhere really) makes you look wildly ignorant on this issue.

Re: Why we are unlikely to ever leave the solar system.

#167

Post by lutorm » Sat, Jun 11, 2011, 2:58 AM UTC

jules wrote: post #152

Confusion wrote: post #102

Earlier quoted context omitted.

There is a minimum amount of mass necessary for an object to be able to collapse upon itself and form a black hole, such as a large star does when the outward pressure due to the internal fusion reaction stalls. However, any amount of mass can (in classical theory) be compressed far enough to obtain a Schwarzschild radius, from which light cannot escape. This has only to do with the density, not the total mass: a ver…

So you could say that all point masses (e.g. electrons) are black holes? What happens if you take a large black hole, and you throw a lot of electrons into it? Does it get an electric field measurable from the outside? If not, how come an electron does have this field?

An electron is only a point mass in classical electrodynamics, which leads to all kinds of inconsistencies (the self-energy of its field would be infinite, for example.) In quantum mechanics, there is no such thing as a point mass.

But in any case, the answer to your question is yes. Black holes have 3 quantities: mass, angular momentum, and charge. So, yeah, you can charge up a black hole by dropping charges into it and the charge would be visible to the outside.

Re: Why we are unlikely to ever leave the solar system.

#168

Post by lutorm » Sat, Jun 11, 2011, 3:04 AM UTC

adrianN wrote: post #83

troels wrote: post #80

Earlier quoted context omitted.

? I thought it was the mass that made a black hole - not the density ?

No, you just require a sufficient pressure to overcome the repulsive forces between the particles to collapse them to a singularity. That's why people were afraid of the LHC.

"just"...

Nuclear matter is very stiff. It can make a mass of the order of the Sun's, falling down with a significant fraction of the speed of light, bounce without becoming a black hole. So the pressure you'd need to make a black hole with higher-than-nuclear density would be, well, astronomical.

Re: Why we are unlikely to ever leave the solar system.

#169

Post by [deleted] » Sat, Jun 11, 2011, 3:34 AM UTC

weavejester wrote: post #113

Given that several Stross novels deal with uploaded intelligence, I was surprised that no mention of this was made. In Accelerando, for instance, his characters travel three light years in a coke-can sized spaceship powered by a laser stationed around Jupiter. It seems unlikely at best that we'll ever attempt interstellar travel in our current organic bodies. The idea of taking along an atmosphere, food, water, and e…

[deleted]

Re: Why we are unlikely to ever leave the solar system.

#170

Post by [deleted] » Sat, Jun 11, 2011, 3:36 AM UTC

weavejester wrote: post #113

Given that several Stross novels deal with uploaded intelligence, I was surprised that no mention of this was made. In Accelerando, for instance, his characters travel three light years in a coke-can sized spaceship powered by a laser stationed around Jupiter. It seems unlikely at best that we'll ever attempt interstellar travel in our current organic bodies. The idea of taking along an atmosphere, food, water, and e…

[deleted]